The present invention relates to a system for controlling fuel injection for a gasoline engine, in which the number of cylinders supplied with fuel is selected in accordance with the load on the engine, whereby the total, that is the number of operating cylinders can be controlled. Such an engine is called a multiple-displacement engine.
In order to adjust the output of a conventional engine having a carburetor, the amount of intake air-fuel mixture is adjusted by the actuation of a throttle valve, keeping all of the cylinders in operating condition. In such an engine, at light load, pumping losses are comparatively large, which results in an increase of fuel consumption.
As an improvement system, a multiple-displacement engine has been proposed in which the number of operating cylinders is changed by stopping operation of intake and exhaust valves of selected cylinders or cutting off the fuel supply in order to fully operate the remaining cylinders to improve fuel consumption.
Japanese patent laid-open specification No. 53-21327 and Japanese patent publication No. 54-266 disclose such systems. However, in these systems, since only predetermined particular cylinders idle without firing, the temperature of the particular cylinders decreases, which is disadvantageous to engine operation.